Australia's fossil past

Australia, the world's oldest visible geology

Ediacara fossils from the Flinders Ranges. Photograph courtesy of the Australian Heritage Council.

A fossil is the impression of a living organism that has been preserved. Fossils are preserved in substances such as sediments, coal, tar, oil, amber, or frozen in ice. There are three main types of fossils: body, trace and chemical.

As well as body fossils, which are actual skeletal remains, there are impressions of soft animals, plants and footprints which have been left as mud hardened. Chemical fossils are the organic compounds and microscopic organisms that have left their mark in the rocks.

Large numbers of fossils indicate that an enormous number of plants and animals have lived on Earth since life evolved more than 3,500 million years ago.

Because of its relative isolation over millennia, Australia has a rich, unique fossil record, dating from approximately 3.2 billion years ago, close to when the Earth was stabilising its formation. Since separation of the former continent Gondwana, an almost continuous record of the distant past is present in Australia today. This includes Pleistocene era Aboriginal body fossils, many of which were removed and sent overseas. The repatriation of many of these human remains is now being negotiated.

Fossil sites

Riversleigh, north-west Queensland, one of the most important fossil sites in the world. Photograph courtesy of the Department of Sustainability, Environment, Water, Population and Communities.

Australia has the world's best example of dinosaur tracks. At the heritage listed Dinosaur Stampede National Monument, near Winton, Queensland, it is possible to see where nearly 200 dinosaurs left about 30,000 footprints. Because of the likelihood of theft or damage, important fossil sites in Australia are protected, and often kept secret.

The Riversleigh fossil site, near Mount Isa Queensland, is recognised as one of the most important fossil sites in the world. Large, now extinct, crocodiles, carnivorous kangaroos and enormous birds are some of the unusual animals that have been identified and studied from fossils. Consequently, there are very few small mammal fossils at the Riversleigh site due to the large predators.The fossils are now displayed at the Riversleigh Fossil Centre. The Riversleigh and Narracoote (SA) fossil sites together form the World Heritage Australian Fossil Mammal Site. They are also on the National Heritage List.

The Darling Downs region contains fossilised remains of prehistoric megafauna - gigantic creatures such as large goannas, kangaroos and giant horned turtles. The megafauna lived during the Pleistocene epoch (1.8 million to 11,550 years BP), and included Diprotodon opatatum that grew as large as a rhinoceros and Thylacoleo carnifex, a marsupial lion.

The Nullarbor Plains also has a fossil site in an underground cavern where the skeletons of Thylacoleo and other species were discovered, such as giant wombats the size of cars, birds and a kangaroo with horns above its eyes.

Fossil finds have suggested the relatively recent arrival of marsupials. Fossils at Lightning Ridge reveal that 110 million years ago Australia supported a number of different monotremes (egg-laying mammals), but did not support any marsupials. The first evidence of marsupials in Australia comes from the 55 million-year-old fossil site at Murgon in southern Queensland.

Palaeontologists

There are many eminent palaeontologists in Australia, including Michael Archer (University of New South Wales), Malcolm Walter (Macquarie University, Neil Archbold (Deakin University), Neil Marshall, Alan Partridge, David Haig (University of Western Australia), John Laurie (Geoscience Australia), Dana Milder and John Mortimer.

Key institutions include the Australian Museum, whose collection includes 'Eric', the opalised pliosaur from Coober Pedy. Both Museum Victoria and the South Australian Museum hold significant fossil collections. The Queensland Museum is responsible for collecting, describing and storing the rich fossil heritage of Queensland.

Geological time periods

Palaeontologists subdivide the four geological time periods that define geological events occurred in Earth's history, to reflect important apparent changes in flora and fauna.

The age of a fossil may be determined using isotope dating, but this is only accurate to within 50,000 years with a 500 year margin of error. The surrounding rock may also be dated in this way. This process is explained in detail by the Australian Museum.

Precambrian Era (more than 545 million years ago)

Very little was known of life in this period until the discovery in 1946 of fossils of soft-bodied animals at Ediacara in the Flinders Ranges, South Australia. Since then, the oldest recorded life forms were discovered at North Pole Dome (near Marble Bar) in the Pilbara region of Western Australia. These microbes, known as stromatolites, have been estimated to be 3.2 billion years old. According to the Australian Centre for Astrobiology, the proximity of the age of these microbes is significantly close to the stabilisation of the planet after its formation.

Ediacara Period (600 to 543 million years ago)

The enormous importance of the Ediacara find led to the naming of this geological period after the area. Many of the fossils may now been seen in the South Australian Museum. Some of the organisms seem to be similar to living samples. Others appear to be extinct today.

Palaeozoic Era (543 to 248 million years ago)

This era is usually divided into six periods. Much of the highland area of Victoria dates from this period. Museum Victoria records that most of these rocks were deposited in an ancient sea.

The Cambrian Period (543 to 490 million years ago) is also known as the 'Age of Trilobites'. Beginning with life in the sea, it also marks the first signs of vertebrate life forms. The Ordovician Period (490 to 443 million years ago) is noted for Graptolites, a form of invertebrate plankton. It is in the Silurian Period (443 to 417 million years ago) that the first evidence of land-based plants and animals were found. Land tracks of a giant water scorpion called Eurypterid have been found in Kalbarri, Western Australia.

During the Devonian Period (417 to 354 million years ago) there was an explosion of life forms including fish, amphibians, insects, spiders, ferns and seed-ferns. The 'Coal Age' or Carboniferous Period (354 to 290 million years ago) refers to the period when forests flourished. These forests formed our present coal deposits. During the Permian Period (290 to 248 million years ago) fossil deposits rich in mammal, reptile and insect specimens, as well as a diverse number of plants, were formed. The era ended with the third, and most catastrophic, extinction event in recorded history.

Mesozoic Era (248 to 65 million years ago)

Muttaburrasaurus langdoni, named after the town of Muttaburra in Queensland. Image courtesy of the Queensland Museum.

Since the discovery of the first fossils of this era, it has become the most publicised and popularised of all. It saw the rise and fall of the largest creatures to live on this planet. This was the 'Age of the Dinosaurs'. The era begins with the Triassic Period (248 to 206 million years ago). A large number of fossils have been found in the Arcadia Formation in the Rewan area of Queensland, the Blina Shale in Western Australia, the Knocklofty Formation near Hobart, Tasmania and the Sydney Basin.

During the Jurassic Period (206 to 144 million years ago) Australia was home to the Rhoetosaurus, one of the world's oldest sauropods. The Cretaceous Period (144 to 65 million years ago) is marked by the discovery of Australia's largest dinosaur, 'Elliot' in 1999 and the Muttaburrasaurus, named after the town of Muttaburra in Queensland. The world's best example of dinosaur tracks is also to be found in Queensland, discovered near Winton in the 1960s.

Cainozoic Era (65 million years ago to present day)

There has been much recent activity in the discovery of fossils of this era. There are two time sub-divisions.

The Tertiary Sub-era (65 to 1.78 million years ago) has been revealed through the exploration of several sites. Fossils found at Lightning Ridge suggest that 110 million years ago Australia supported a number of different monotremes, but did not support any marsupials. Marsupials appear to have evolved in the northern hemisphere about 95 million years ago and spread to South America.

The first evidence we have of marsupials in Australia comes from the 55 million-year-old fossil site at Murgon in southern Queensland. This Murgon site has yielded a range of marsupial fossils, many with strong South American connections. At Murgon there is also evidence of a placental mammal, known as a condylarth. Placental mammals were also found in North America and South America at this time.

After decades of work a collaboration between more than 80 scientists at a number of key fossil sites in Australia an amazing array of strange, unexpected beasts are being discovered. Undoubtedly the key sites in this understanding are Riversleigh in north-west Queensland (added to the World Heritage List in 1994) and Naracoorte in South Australia. The fossils from Riversleigh represent an almost complete story of the evolution of Australia's terrestrial ecosystems over the past 25 million years. Riversleigh has been recognised as one of the most important fossil sites in the world.

The Quaternary division (1.78 million years ago to present day) marks the beginnings of Homo sapiens. The age of the origins of humans in Australia is hotly debated by the experts, but skeletal remains like those at Lake Mungo in New South Wales, by Jim Bowler in February 1974, have been dated between 15,000 and 50,000 years old. John Mulvaney's work at Kenniff Cave between 1960 and 1963, established Aboriginal occupation of Australia many thousands of years into the Pleistocene (Quaternary).

Pleistocene epoch (1.8 million to 11,550 years BP) and Aboriginal body fossils

A cast of the skeleton of the giant Pleistocene wallaby, Protemnodon. Photograph courtesy of the South Australian Museum.

Australian Aboriginal body fossils

Great care is now taken to balance palaeontological and archaeological interest in Aboriginal heritage and material culture with protecting the rights of Aboriginal peoples and their sacred burial sites. Aboriginal material culture is often part of a study program with palaeontology. Previously, palaeontological study of Australian Aboriginal body fossils involved the practice of scientific investigation of Aboriginal remains. These remains had often been removed from burial sites and were stored in boxes and bags in museums, both overseas and in Australia.

In 2002, ATSIC identified more than 50 institutions in 18 countries which acknowledged holding Aboriginal remains in their collections.

Indigenous remains held in museums overseas

The Royal College of Surgeons became the first English institution to hand over Aboriginal remains in 2002. Among them were said to be the hair and skin of Truganini, a Tasmanian Aboriginal leader, who died in 1878. Other Aboriginal leaders such as Pemulwuy, a Bura man of the Eora people Sydney, and Yagan of the Tondaryo Ballaruk clan of the Nyungar people of south-western Australia, had their heads severed and pickled. It is Aboriginal belief that while skeletal remains are incomplete, the person's spirit remains earthbound, unable to continue its eternal journey (Ken Colbung, 2003).

In 2007, Britain's Natural History Museum and the Tasmanian Aboriginal Centre finally reached a conclusion to the 20 year negotiations for the repatriation of human remains. The remains of 17 Tasmanian Aborigines were reclaimed from the museum. The museum, which had wanted to conduct scientific tests on the bones before they were returned, dropped this demand. The two parties agreed to share responsibility for DNA already taken from the remains by storing the material in Tasmania.

In 2009 the remains of 17 Indigenous Australians were handed over to a delegation of Aboriginal people from the Kimberley region in Western Australia and Moreton Bay in Queensland at a ceremony in Austria.

A traditional smoking ceremony was performed by Kimberley men, Terry Murray and Tom Lawford to cleanse the remains in preparation for their journey home. The remains from the Goorenpul community of Moreton Bay, Queensland were handed to community representative Jody Coghill. The Pathology and Natural History Museum in Vienna handed over the remains. Some of the remains will be brought back to the National Museum of Australia.

Australian Museums

The return of remains has also been initiated by Australian museums. Recently, the skeleton of an Aboriginal man, Dick Cubadjee, a Warumangu man, was returned to his descendents for burial in his traditional country near Tennant Creek. Cubadjee acted as a tracker and interpreter for explorer David Lindsay in the 1880s.

In 2005, the Australian Museum and the National Museum of Australia returned the remains of 11 adults and 3 children, members of the Ku-ring-gai clan, near Manly, whose bones had been displayed for more than a century. The remains were repatriated to a site which was close to where they lived in Manly, in negotiation with the NSW National Parks and Wildlife Service and the Metropolitan Aboriginal Land Council. In a private ceremony, the bones were wrapped in paperbark and smoking ceremonies were conducted to accompany the burials.

Repatriation of and respect for Indigenous remains

Today, a balance is sought between the needs as defined by scientific investigation and the needs of the descendants of Aboriginal people whose bodily remains were removed to museums as body fossils, to allow these people to 'rest in peace'.

More than 1,000 Aboriginal ancestral remains are held in museums around the world. Since 1990, more than 1,150 Indigenous remains have been brought back to Australia.

The Aboriginal and Torres Strait Islander Protection Act 1984 and state parks and wildlife acts include some responsibility for Aboriginal remains, including the Victorian Government which has strict regulations about not disturbing burial sites.